We're talking about PCBs here, the unpopulated (or stripped in this case) boards. The components are easy to take off, especially if you're only after the metals. As I understand it, the heavy metals are in the soil, the danger is that plants and animals will ingest these. So we clean up by putting substances on/in the soil that absorb the heavy metals more readily and result in something that is less harmful. The idea is that PCBs (which are toxic waste in same places) can be made into something useful. I would be interested in how it compares to the current best in breed methods for dealing with heavy metals, since we're still cleaning up from the roman's digging up half the world :)
The quick, dirty and not too efficient way is to do it with excess heat applied. Can do it a bit more carefully on something semi regulated (I've field repaired* surface mount kit with reflowing from electic hotplates, an iron, and once a cast iron skillet) and pick off the components. The most efficient way is crushing it all then dissolving the metals in acid (leeching), and extracting from the acid.
You can get refiners to process your boards for you, I get much more for taking the working chips off and selling them on (as used, no scamming here), and getting the odd 200-300g of random parts melted and assayed. Anyone going on about the value of gold in old electronic systems is usually missing the point. The silvery metals are more plentiful in there, and worth 50-100% of gold's value. Gold is usually somewhere between 3rd and 5th of the total value of assays from IT scrap (CPU and RAM for more gold connections, pure CPU will get you more). YYMV but the only places I've gotten "free" gold from in decent amounts (10g+) is metal detecting (bah, me hates it) and gold panning in NZ and Oz. Panning costs sod all (pan, magnets, couple little squigy bottles, digging implement maybe 50 bucks) and pays better than minimum wage in NZ. Oz kills me in like 3 of 4 seasons, so it may be amazing, but I hide inside there.
Like with all scrap (and all commodities, as I'm sure our resident brokers will agree) it depends a great deal on where you are selling it. You can almost always get more for the finished product than in scrap. Had dead towers that I got more from selling the case than from the guts, since it had a pretty case. Had stuff I was certain that would sell (mobo+cpu+ram bundles) that never did, and things I listed as an afterthought (8x CD-RW drives, 230 watt PSU, dead hard drives) sell like hot cakes.
Oh, just thought of the other place for gold. Rag picking, old dumped boxes and house clearances. Damaged jewellery etc. People been hoarding gold for long times.
* As in got working until a replacement came in. This is not suggested, for engineering or OSH reasons.
Biting the hand that feeds IT
